Chest CT scan is a layered scan of the anatomical structures of the chest cavity using X-rays. It is used to clarify the nature of injuries and diseases of the thoracic cavity: diagnosis of fractures of the rib cage and sternum, lung atelectasis, hemo- and pneumothorax, hemopericardium and other pathologies. It is usually a clarifying method of investigation, is prescribed after radiography of the chest organs, is performed without the introduction of a contrast agent (native) or using contrast.
Indications
Chest CT scan is a popular study in pulmonology, traumatology, oncology. This is an absolutely non-invasive technique, which, if technically possible, can be used as an express diagnosis and screening. CT is performed after an overview or targeted chest X-ray, if necessary, to detail the data of the X-ray examination. Indications for computed tomography can serve as:
- lung neoplasms: lung cancer, pleural mesothelioma;
- mediastinal tumors: thymomas, lymphomas, cysts, mediastinal metastases; lymphogranulomatosis;
- infectious diseases: pneumonia (including caused by the new coronavirus infection COVID-19), abscess, pulmonary tuberculosis;
- chest injuries accompanied by rib fractures, sternum fractures, internal organ damage (lung rupture, hydro- and pneumothorax, hemopericardium);
- vascular lesions: PE, arteriovenous aneurysm;
- interstitial lung diseases: pneumomycosis, pneumoconiosis, etc.
Chest CT scan makes it possible to detect latent pathological processes and tumors at the earliest stages of development, and contrast enhancement allows you to clarify the degree of prevalence of the process, to conduct a differential diagnosis.
Contraindications
Due to ionizing radiation, chest CT scan is not recommended for use during the examination of children and pregnant women (except in cases when the scan is carried out for vital indications). The inability to hold your breath for the time required for tomography of one layer is also regarded as a contraindication to computed tomography of the chest.
In addition, the diagnostic technique is not used in a serious condition of the patient, requiring constant monitoring of vital signs and support of the life support system. The technical limitation is an excess weight of more than 120 kg. Contraindications to the use of iodine-containing contrast are:
- allergy to iodine;
- chronic renal and hepatic insufficiency;
- hyperthyroidism;
- myeloma disease;
- bronchial asthma or severe diabetes mellitus.
Preparation
No special training is required for native chest CT scan. Contrast enhancement is used for oncopoisk, the need to stage the oncological process, the diagnosis of vascular anomalies and PE. The drug is administered intravenously bolus. To exclude the risk of adverse reactions, an additional examination is prescribed before a contrast CT scan of the chest: a biochemical blood test (urea, creatinine, transaminases), an allergy test for the drug. Contrast tomography is performed on an empty stomach.
Methodology of conducting
The patient is placed on a moving couch of the device, if necessary, a contrast agent is injected and moved under the ring of the tomograph. A series of snapshots are taken at certain intervals. The projections and the width of the tomographic layer are determined by the localization and nature of the pathology.
The standard scanning step for chest CT scan is 0.5-1 cm. Sometimes it is advisable to conduct a study with the allocation of a wider layer (from 2 to 2.5 cm). The technique is called zonography, it allows you to simplify the search for the affected area, in a shorter time to determine the volume and degree of violation of lung ventilation. In the presence of indications, chest CT scan can be combined with virtual bronchoscopy.
